WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7150

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Access Right: Closed AccessAuthor: search.filters.author.Ballar Kırmızıbayrak, Petek

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  • Conference Object
    Citation - WoS: 1
    Secondary Metabolites From Endophytic Fungus Penicilium Roseopurpureum and Investigation of Their Cytotoxic Activities
    (Georg Thieme Verlag, 2022) Dizmen, Berivan; Dizmen, Berivan; Üner, Göklem; Bedir, Erdal; Küçüksolak, Melis; Üner, Göklem; Ballar Kırmızıbayrak, Petek; Küçüksolak, Melis; Bedir, Erdal; 03.01. Department of Bioengineering; 01. Izmir Institute of Technology; 03. Faculty of Engineering
    [No Abstract Available]
  • Conference Object
    Citation - WoS: 1
    Phytochemical Studies on Mastic Gum of Pistacia Lentiscus Var. Chia Collected From Karaburun Peninsula and Neuroprotective Activities of the Isolates
    (Georg Thieme Verlag, 2022) Demir, Mehmet; Üner, Göklem; Üner, Göklem; Demir, Mustafa Muammer; Mu, Kurt; Bedir, Erdal; Aygün, M.; Ballar Kırmızıbayrak, Petek; Bedir, Erdal; 03.01. Department of Bioengineering; 01. Izmir Institute of Technology; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering
    [No Abstract Available]
  • Conference Object
    Short Lecture Novel Neuroprotective Metabolites Produced Via Biotransformation of Cyclocephagenol by Alternaria Eureka 1e1bl1
    (Georg Thieme Verlag, 2022) Küçüksolak, Melis; Üner, Göklem; Üner, Göklem; Bedir, Erdal; Ballar Kırmızıbayrak, Petek; Küçüksolak, Melis; Bedir, Erdal; 03.01. Department of Bioengineering; 01. Izmir Institute of Technology; 03. Faculty of Engineering
    Neurodegeneration refers to the loss of structure/function of neurons leading to neurological diseases including Alzheimerʼs and Parkinsonʼs. The discovery of novel therapeutics against neurodegenerative diseases has been an area of intense research as neurodegenerative diseases are a huge burden on society and the economy [1]. Numerous studies reported that natural products have the potential to prevent and treat neurodegeneration. Among these studies, the neuroprotective activities of cycloartane-type saponins are noteworthy [2], [3]. In our preliminary studies, the neuroprotective activity of cyclocephagenol, an aglycone of cyclocephaloside I from Astragalus microcephalus [4], was screened for H2O2-induced injury in SH-SY5Y cells. Based on the promising bioactivity of cyclocephagenol, the aims of this study were: i) to perform microbial transformation studies on cyclocephagenol using Alternaria eureka followed by isolation and structural characterization of the metabolites; ii) to investigate neuroprotective activities of the metabolites; iii) to understand structure-activity relationships towards neuroprotection.
  • Article
    Citation - WoS: 19
    Citation - Scopus: 21
    Telomerase Activators From 20(27)-Octanor Via Biotransformation by the Fungal Endophytes
    (Academic Press, 2021) Duman, Seda; Bedir, Erdal; Yılmaz, Sinem; Yusufoğlu, Hasan; Ballar Kırmızıbayrak, Petek; Bedir, Erdal; 03.01. Department of Bioengineering; 01.01. Units Affiliated to the Rectorate; 01. Izmir Institute of Technology; 03. Faculty of Engineering
    Cycloastragenol [20(R),24(S)-epoxy-3 beta,6 alpha,16 beta,25-tetrahydroxycycloartane] (CA), the principle sapogenol of many cycloartane-type glycosides found in Astragalus genus, is currently the only natural product in the anti-aging market as telomerase activator. Here, we report biotransformation of 20(27)-octanor-cycloastragenol (1), a thermal degradation product of CA, using Astragalus species originated endophytic fungi, viz. Penicillium roseopurpureum, Alternaria eureka, Neosartorya hiratsukae and Camarosporium laburnicola. Fifteen new biotransformation products (2-16) were isolated, and their structures were established by NMR and HRESIMS. Endophytic fungi were found to be capable of performing hydroxylation, oxidation, ring cleavage-methyl migration, dehydrogenation and Baeyer-Villiger type oxidation reactions on the starting compound (1), which would be difficult to achieve by conventional synthetic methods. In addition, the ability of the metabolites to increase telomerase activation in Hekn cells was evaluated, which showed from 1.08 to 12.4-fold activation compared to the control cells treated with DMSO. Among the compounds tested, 10, 11 and 12 were found to be the most potent in terms of telomerase activation with 12.40-, 7.89- and 5.43-fold increase, respectively (at 0.1, 2 and 10 nM concentrations, respectively).
  • Article
    Citation - WoS: 34
    Citation - Scopus: 39
    Aptamer-Based Electrochemical Biosensing Strategy Toward Human Non-Small Cell Lung Cancer Using Polyacrylonitrile/Polypyrrole Nanofibers
    (Springer, 2020) Kıvrak, Ezgi; Yılmaz, Selahattin; İnce Yardımcı, Atike; İlhan, Recep; Ballar Kırmızıbayrak, Petek; Yılmaz, Selahattin; Kara, Pınar; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    In the present study, a sensitive electrochemical aptamer-based biosensing strategy for human non-small cell lung cancer (NSCLC) detection was proposed using nanofiber-modified disposable pencil graphite electrodes (PGEs). The composite nanofiber was comprised of polyacrylonitrile (PAN) and polypyrrole (PPy) polymers, and fabrication of the nanofibers was accomplished using electrospinning process onto PGEs. Development of the nanofibers was confirmed using scanning electron microscopy (SEM). The high-affinity 5 '-aminohexyl-linked aptamer was immobilized onto a PAN/PPy composite nanofiber-modified sensor surface via covalent bonding strategy. After incubation with NSCLC living cells (A549 cell line) at 37.5 degrees C, the recognition between aptamer and target cells was monitored by electrochemical impedance spectroscopy (EIS). The selectivity of the aptasensor was evaluated using nonspecific human cervical cancer cells (HeLa) and a nonspecific aptamer sequence. The proposed electrochemical aptasensor showed high sensitivity toward A549 cells with a detection limit of 1.2 x 10(3)cells/mL. The results indicate that our label-free electrochemical aptasensor has great potential in the design of aptasensors for the diagnostics of other types of cancer cells with broad detection capability in clinical analysis.
  • Conference Object
    A New Semi-Synthetic Sapogenol Derivative Inducing Regulated Necrosis
    (Georg Thieme Verlag, 2019) Üner, Göklem; Bedir, Erdal; Ballar Kırmızıbayrak, Petek; Üner, Göklem; Bedir, Erdal; 03.01. Department of Bioengineering; 01. Izmir Institute of Technology; 03. Faculty of Engineering
    Since saponin’s antitumor potency is relatively weak, researchers focus on their semi-synthetic modification to obtain structures with higher potencies. With the same motivation, we prepared a cytotoxic sapogenol derivative (AG-08) from cycloastragenol. Our preliminary studies revealed that AG-08 induced primarily necrotic cell death along with autophagic inhibition. Furthermore, immunoblotting experiments demonstrated that AG-08 promoted cleavage of various proteins such as ATGs, p62, and PARP-1.
  • Conference Object
    Citation - WoS: 1
    Telomerase Activators Derived From Astragalus Sapogenins Via Biotransformation With the Recently Discovered Endophytic Fungus Camarosporium Laburnicola
    (Georg Thieme Verlag, 2019) Küçüksolak, Melis; Yılmaz, Sinem; Ekiz, Güner; Duman, Seda; Duman, Seda; Bedir, Erdal; Yılmaz, Sinem; Küçüksolak, Melis; Ballar Kırmızıbayrak, Petek; Bedir, Erdal; 03.01. Department of Bioengineering; 01.01. Units Affiliated to the Rectorate; 01. Izmir Institute of Technology; 03. Faculty of Engineering
    Telomeres are nucleotide sequences that are located at the end of chromosomes shortening with each cell division. Telomerase is a reverse transcriptase enzyme, and it helps to replenish telomere ends that are truncated by aging and stress factors.
  • Article
    Citation - WoS: 23
    Citation - Scopus: 22
    Microbial Transformation of Cycloastragenol and Astragenol by Endophytic Fungi Isolated From Astragalus Species
    (American Chemical Society, 2019) Ekiz, Güner; Bedir, Erdal; Yılmaz, Sinem; Ballar Kırmızıbayrak, Petek; Bedir, Erdal; 03.01. Department of Bioengineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Biotransformation of Astragalus sapogenins (cycloastragenol (1) and astragenol (2)) by Astragalus species originated endophytic fungi resulted in the production of five new metabolites (3, 7, 10, 12, 14) together with 10 known compounds. The structures of the new compounds were established by NMR spectroscopic and HRMS analysis. Oxygenation, oxidation, epoxidation, dehydrogenation, and ring cleavage reactions were observed on the cycloartane (9,19-cyclolanostane) nucleus. The ability of the compounds to increase telomerase activity in neonatal cells was also evaluated. After prescreening studies to define potent telomerase activators, four compounds were selected for subsequent bioassays. These were performed using very low doses ranging from 0.1 to 30 nM compared to the control cells treated with DMSO. The positive control cycloastragenol and 8 were found to be the most active compounds, with 5.2- (2 nM) and 5.1- (0.5 nM) fold activations versus DMSO, respectively. At the lowest dose of 0.1 nM, compounds 4 and 13 provided 3.5- and 3.8-fold activations, respectively, while cycloastragenol showed a limited activation (1.5-fold).